Core bit and retrieving core barrel



f Dec. 17, 1935.

T. N. HUNT CORE BIT AND RETRIEVING CORE BARREL 2 Sheets-Sheet 1 Filed Nov. 27, 1933 Dec. 17, 1935. T, N, HUNT 2,024,450

CORE BIT AND RETRIEVING CORE BARREL Filed Nov. 27, 1955 2 Sheets-Sheet 2- :9

Patented Dec. 17, 1935 UNITED STAT-ES PATENT OFFICE 2,021,450 CORE BIT AND RETRIEVING CORE BARREL Thomas N. Hunt, Houston, Tex

Application November 2:7, 1933, Serial No. 699,894

4 Claims. (01. 25:42)

My invention relates to core bits for drilling deep wells in which a core barrel is provided which may be inserted downwardly throughthe drill stem to a seat in the bit to receive a core and again withdrawn fromthe drill stem when the core has been taken. Q

It is an object of the'invention to provide a bit for use with the retrievable core barrel,

which has a detachable cutting element thereon which may be removed for repair or sharpening without the necessity of removing the head of the bit. I desire to provide a. removable cutter vide a core barrel which may be used with a roller core bit and to provide, in connection with the same, means for keeping the seat for the core barrel clear of mud or sand 'or other obstructions so that the barrel may be accurately seated in'obtaining the core.

The invention contemplates the provision along with a roller core bit of openings in the side of the core barrel adjacent the rolling cut-. ters which will allow the circulation of fluid inwardly or outwardly across the core barrel seat so that it may be constantlywashed clear of material.

In the drawings herewith, Fig.1 is a side view partly in elevation and partly in central vertical section'illustrating the application of my invention to a drill of the flshtail type, having a removable blade.

Fig. 2' is a similar view taken at right angles to the view shown in Fig. 1.

'Fig. 3 is a top plan view of the cutting blade removed from the bit head. r

Fig. 4 is an assembly view showing the drill,

. the drill collar, and the connections thereof beingtaken on th'e'plane 5-5 of Fig. 7. a Fig. '6 is 'asimilar longitudinal section taken on-the plane 6-6 of Fig.7.

Fi'g. 7-is a bottom plan view of this embodiment of the invention.

3 .In theembodiment ofthe invention disclosed in Figs. 1 to 4, inclusive, 1 have shown a core bit of the fishtail type. There is a head I approximately cylindrical in shape and having an upper tapered shank 2 threaded to engage within the drill collar 3. The head I is flattened on 5 opposite sides, as shown at 4, and extended downwardly a short distance? This lower extention 4 has transversely thereof a slot 5, the walls 5 of which converge upwardly to provide a seat to receive the shank 6 of the/bit and 10 I to provide a wedging flttherefor.

The cutting blade I is of the usual fishtail type, having its lower end formed into two cutting edges 8 and 9, one edge being inclined in one direction and one in the other, so that a' forwardly inclined cutter is presented in the direction of rotation of the bit at both sides thereof. Axially of the blade is a longitudinal opening to receive the core bit It. Said core bit may or may not extend its lower end in ad- 20 vance of the cutting edge of the blade. In the drawings it'is shown as projecting slightly below the blade to form a core cutter II. Thetubular body of the bit projects upwardly above the shank 6 of the bit and fits within a longi- 25 vtudinal opening l2 in the head ofthe drill. The

tubular passage through the core bit is flared outwardly at its upper end, as shown at l3, to direct the core barrel downwardly into its seat in the bit. I

The core bit has a lateral opening It on opposite sides thereoi' along'the flat face of the main bit. This opening is inclined inwardly from the upper end toward the lower end"l5, said lower end providing a shoulder as seen in Fig. 2. 35 The interior of the core bit is provided with. a downwardly tapered seat, shown at IS, in Figs. 1 and 2, said seat being immediately below V the lower end l5 of the lateral opening or window in the bit.- This opening allows the cir- 40 culation of flushing fluid, directly through the core bit so that there wilLbe 'no chance of clogging this opening and the circulation of fluid therethrough will keep the seat It continually washed clear of any material tending to clog the 45 same.

The detachable blade with the core bit secured thereon is mounted in the head of the bit by extending the core bit upwardly into the opening l2 and the tapered shank 6 of'the blade into 50 the tapered slot 5 in the bithead; The. parts are then fixed rigidly in position by through bolts l8, there being two of --these bolts, one at each side, extending through the walls of the head and through the shank 6 of theblade. 55

These bolts l8 are preferably tapered and the openings in theblade are slightly elongated which enables the operator in inserting the bolt to wedge the blade upwardly into the head when the bolt is driven therethrough.

In the operation of this bit the core barrel I9 may be lowered downwardly through the drill stem and into position upon the seat [6 at any time when'a core is to be taken. It will be understood that when the core barrel is notin position-the flushing fluid will circulate downwardly through the opening l2 in the bit and through the core bit and against the material at the bottom of the hole. There are also inclined passages terminating at 20 on the forward side of the head of the bit which allow the discharge. of flushing fluidabove the cutting edge of the blade. However, when the core barrel is not in position the larger proportion of the flushing fluid will pass out through the windows I4 in the side of the core barrel and flush the seat l6 so that no material will clog therein. For this reason when the core barrel is inserted, as previously noted, the core barrel will drop into the seat It and form a close fit therewith. This barrel will then, be latched in place by a latch shown in Fig. 4, at 2|, this portion of the device forming no part of the present invention and will not be more particularly described.

When a core has been taken the overshot may be lowered to engage the upper end of the core barrel and withdraw the same from the hole. It is to be understood that when the core barrel is not in position any core passing upwardly into the core bit will be washed away by the flushing fluid. While the core barrel is in position in the core bit the circulation will be largely through the passages 20 in the head of the bit.

In Figs. 5, 6, and 7., I have shown how it is possible in a roller core bit to provide means for flushing the seat for the core barrel in somewhat the same way as is shown in the first embodiment. In this form of ,bit there is a head I, having a threaded upper shank 2. Upon the head' I are a plurality of radial ribs 22, said ribs extending from the upper shoulder 23 on the bit head downwardly to the lower end. Each of these ribs is of ,suflicient width to provide a support for a rolling cutter. The lower end of each rib is slotted, as shown at 24 and. 25, to receive rolling cutters 26 and 21, respectively. As will be seen from Fig. 7, six cutters may be used and I contemplate arranging these cutters in sets of three, one set of cutters 26 being inclined upwardly at their inner ends and the .other set 21 being inclined downwardly at their inner ends, the latter set being arranged to have their outer margins 28 cut the outer wall of the hole while the other set 26 at their inner ends 29 cut the inner wall of the hole adjacent the core.

Each of the cutters is mount'edbn an inclined cutter shaft "30, the ends of which are supported in the head of the bit, including the said ribs 22, and flushing fluid is carried downwardly to each of the cutters through a channel 3| in the bit head. I

Centrally of the head is a longitudinal passage l2 and ;in the lower end of said passage is fixed the corebit head Ill. The lower endof the head projects downwardly and has a series of cutting teeth thereon to cut a core on the bottom of' the hole. This core bit is shown as extending slightly in advance of the main cutters but it is to be understood that it may be set in any desirable position in advance or above the level of the cutting rollers. As will be seen from the drawings, the core bit is formed with an interior shoulder l6 beveled to form a seat to receive the core barrel l9, this seat being in all respect similar to that shown iii the previous embodiment.

To maintain the seat I6 in this form of bit free of material, I form lateral slots H in the wall of the core bit head ID at a point spaced closely above the said seat I6. I form one of said slots l4 between each set of cutters, as shown in Fig. '7. These slots are longitudinal openings in the side wall of the core bit head which allow, in the normal operation of the bit, a circulation through the said openings during the time when the core barrel is not in position. When the core barrel is lowered to its seat these openings will be closed and the circulation will be entirely through the longitudinal passages 3f leading to the cutters.

With this arrangement it' is possible in the roller core bit to maintain a clear seat for the core barrel at all timesso that when the core barrel is lowered to position I am ass d that the barrel will drop to its seat and be maintained in' a position to properly engage the core.

The advantages of this construction lie in the accurate and efficient manner in which the core 30 barrel is seated. By maintaining the seat for the removable barrel clear at all timesthe difticulty which is usually encountered with removable core barrels is entirely overcome. There will be no failure of the core barrel to properly seat and receive the core and a successful core may be taken in formations where otherwise it has been found almost impossible.

What I claim is:

l. A well drill including a head, a plurality of 40 radially extending longitudinal ribs thereon, rolling cutters mounted in the lower end of saidhead and said ribs, an axial core bit opening in said head, a core bit therein extending in advance of said rolling cutters, a seat in said core bit, a core barrel adapted to be lowered to said seat and a plurality of slotted openings in said head and core bit above said seat.

2. A well drill including a tubular head, radial, longitudinally extending ribs on said head, rolling cutters mounted at the lower end of said drill on each of said ribs, a core drill axially of said head, a cutter on the forward end of said core drill,,a core barrel seat in said core drill, said head and said core barrel having slotted openings therein whereby flushing fluid may wash said seati.

3. A core drill including a tubular head, radial, longitudinally extending ribs on said head, rolling cutters mounted at the lower end of said drill on each of said ribs, a core drill axially of said head, a core barrel seat in said drill, said head and said core barrel having slotted openings therein extending radially through the walls thereof between said ribs whereby flushing fluid may wash said seat. 

